Electric clock system



April 14, 1925.

, H. E. WARREN ELECTRIC CLOCK SYSTEM Filed Sept. 27, 1922 I In\/entor':

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Patented Apr. 14, 1925.

UNITED STATES v 1,533,678 PATENT OFFICE.

HENRY E. WARREN, 0F ASHLAND, MASSACHUSETTS, ASSIGNOR '10 WARREN CLOCK COMPANY, A CORPORATION OF MAINE.

ELECTRIC CLOCK SYSTEM.

Application filed September 27, 1922. Serial No. 590,968.

To all whom it may concern:

Be it known that I, HENRY E. VARREN, a citizen of the United States, residing at Ashland, in the county of Middlesex, State of Massachusetts, have invented certain new and useful Improvements in Electric Clock Systems, of which the following is a specification.

My invention relates to electric clock systems and more in particular to a novel thermo-electric clock operating means controlled in response to a time controlled switch at any desired distant point.

My invention is particularly advantageous for clock systems where one or more secondary clocks on a system are operated by or controlled from a master clock over an electric circuit. The primary object of my invention is to provide such a-clock system in which both the master clock and the secondary clock or clocks are extremely simple .-.in construction and operation, without the sacrifice of accuracy. A further object of my invention is an electric clock system which may be operated by either direct or alternating current with a very small consumption of energy. A further object is the provision of a secondary clock which is noiseless in operation, requires no lubricant and is not affected by temperature and weather changes. Other advantages of-my invention will appear as the description proceeds.

In carrying my invention into effect I make use of the thermal expansion and contraction of an intermittently electrically heated wire to operate or control a clock escapement in response to a time controlled electric contact in the energizing circuit of said wire.-

The features of my invention which I believe to be novel and patentable will be pointed out in the claims appended hereto. The details of construction and operation of a preferred form of my invention will now be explained in connection with the accompanying drawing in which Fig. 1 shows a clock system embodying my invention; Fig. 2 shows a cross-section through the type of secondary clock operating escapementshown in Fig. 1; and Fig. 3 shows a modified, secondary clock escapement em;

bodying the broad principle of my inven'- master clock shown here as the spring operated, pendulum controlled type, the dial and hands being omitted. This clock is adjusted to keep accurate time and is arranged to make and break an electric circuit at definite, predetermined time intervals. The circuit control means illustrated consists of a stationary contact 2 arranged to contact with the pendulum 3 at one extremity of its swing. The pendulum is electrically cinnected through wire 4 to a source of electric energy, here shown as a battery I), but which may be any other suitable source of current either direct or alternating.

Connected across battery 5 through the master clock controlled contacts is an outgoing circuit consisting of wires 6 and 7 and connected across this circuit are one or more electro-thermal responsive devices, each consisting of a fine wire 8, arranged to operate a secondary clock 9. The detail of the electro-thermal responsive device is best shown in Fig. 2. The upper end of wire 8 is secured to a spring 10, the upper end of which is secured ,to a stationary support 11 and electrically connected to battery 5 through wire 7. The lower end of wire 8 is secured to a rod 12 threaded intoa stationary support 13 of insulating material. Lock nuts 14 are provided so that the rod 12 may be turned and locked in any desired position toadjust the tension of spring 10 and wire 8 and to provide a terminal by means of which rod 12'and wire 8 may be electrically connected to wire 6. Near the upper end of wire 8 it is passed one or more timesabout a drum. 15 of insulating material rotatively mounted on a stationary shaft 16. Also rotatively mounted on shaft 16is a rachet wheel 17 integral with a gear wheel 18. Between drum 15 and wheel 17 is a friction transmit-ting washer 19 such as leather or cork. Drum 15, washer 19 and wheel 17 are gently pressed together between a pair of collars 20 and ill by means ofa coiled spring The tension on wire- 8 and spring 10 are initially, adjusted so that when the wire is heated by a momentary closing of the electric circuit the spring 10 is under sufiicient tension to keep the wire taut and the length of wire 8 is such that when the wire cools and contracts, it will elongate spring 10 and turn drum 15 a desired small amount. It will now be evident that the alternate heating and cooling of wire 8 due to the making and breaking of the circuit by the master clock will rotate drum 15 first one way and then the other and this movement will, unless prevented, be transmitted to ratchet wheel 17 and gear wheel 18 through the friction washer 19. There are numerous ways ofcausing this thermal responsive device to operate or control a clock movement and the way in which I have chosen to illustrate it in Figs. 1 and 2 consists ina pawl 23' for allowing the rotation of ratchet wheel 17 and gear wheel 18 in one direction only and driving a clock movement from gear 18 through appropri ate reduction gearing designated in general by the numeral 24. It is immaterial,

.- whether the contraction of the wire 8 or the contraction of the spring 10 drives the clock movement forward and infact both of said movements could be utilized for this purpose by providing duplicate mechanisms similar to that shown, on either end of the drum and reversing the direction of rotation of one mechanism by suitable gearing.

In the present illustration I have shown the,

pawl 23 and rachet wheel 17 arranged to prevent the rotation of gear 18 when wire 8 contracts and to allow its rotation when spring 10 contracts. The amount of rotative movement of drum 15 will be made such that ratchet wheel 17 will move in a clockwise direction (referring to Fig. 1) more than one tooth but less than two teeth so that each closing of the circuit by the master clock will always move the secondary clocks forward a. predetermined definite amount. This device therefore comprises an escapement which in addition to performing the function of an escapement drives the clock.

The clock gearing may be made very simple since there is a wide latitude for adjustment between the frequency of oper ation 'of the master clock contactor and the amount of rotative movement produced at the drum 15. For example, the master clock might be arranged tomake and break the control circuit once a minute and the rotative movement of drum 15 made to drive 'the minute hand of the secondary clock through the one-way clutch without inter-' mediate reduction gearing, in which case the rotative movement of the drum would. have to be greater than 6 degrees and less than 12 degrees and the ratchet wheel 17 would be provided with 60. equally spaced teeth. This remarkable range of adjust ability permits the secondary clocks to be made very simply and crudely and therefore very inexpensively and yet operate with absolute accuracy. Since the torque neces- 'sary to drive the secondary clock is very small, the springs 22 and 10 and likewise, the wire 8 may be made as delicate as desirable consistent with reliability. Consequently, only a very small current will be necessary to heat the wire and as many clocks as desired may be operated from the same system. Furthermore, the clock operationis noiseless and so simple as to require no lubricant and the accuracy is not aflfected by ordinary changes in weather conditions. Such a clock will therefore require little if any attention.

The master clock may he of any known type and may control the secondary clock circuit in any desirable way other than that represented.

In Fig. 3 I have shown a modification of the secondary clock where the escapement pawl 25 of an ordinary spring type clock 26 is controlled by a thermal responsive device. In this modification the escapement pawl 25 i is provided with an adjustable weight 27 on one end so as to bias the pawl into the position shown. A thermal respon-' sive wire 8 is arranged to raise and lower the weighted end of pawl 25 in response to a time controlled contact and thus actuate the escapement device to allow the clock gearing to advance in the usual manner. The llustration 'shows the position of the escapement mechanism when the wire 8' is expanded.

In the modification illustrated the thermal responsive wire has been shown in a vertical position. This is not essential however. The lever K of the clock escapement shown in my U. S. Patent 1,191,859,

July 18,1916, might be controlled in a simreading of a meter at one or moge points.

distant from the meter.

What I claim as new and desire tosecure by Letters Patent of the United States, is: 1. An electric clock system comprising an electric circuit, a master clock, a secondary clock, an escapement for said secondary clock, a thermal responsive electric conductor in said circuit for controlling the operating .of said escapement and means controlled by said master clock for periodically energizing said circuit. I

2.'A system for the distribution of time by means of secondary clocks comprisin an electric circuit, a master clock, a secon ary clock, a thermal responsive conductor in said circuit, means controlled by said master clock for periodically energizing said circuit and means connected between said secondary clock and thermal responsaid secondary clock.

3. A system for reproducing motion .at a distant point comprising a moving device,

' an electric circuit, a thermal responsive conductor in said circuit, means controlled by the movement of said device for successively energizin and deenergizing said circuit to respective y produce an expanslon and contraction of said conductor and means controlled by said thermal responsive movements for reproducing the movement of said device.

4. A system for reproducing rotary movements at a distant point comprising a drum, an electric circuit, a thermal responsive wire connected in said circuit and wound about said drum and supported so that its expansion and contraction oscillate said drum, means for obtaining a rotary movement in one direction only from said oscillatory movement, and means operated in res use to the rotary movement to be repro uced for successively energizing said circuit.

5. A time indicating device comprising a dial, an indicating hand cooperating there with, drum, a wire wound about said drum and so supported that changes in its length rotate said drum,means for periodically passing an electric current through said wire to cause the latter to alternately expand and con-tract whereby said drum is oscillated and a one-way driving connection between said drum and hand.

6. A thermal electric motor for operating clocks and the like comprising a shaft, a drum and a ratchet wheel rotatively mounted on said shaft, a friction drivin connection between said drumand wheefi a wire in driving connection with said drum and so supported that changes in its length rotate said drum, means for connecting said vwire to an intermittentl venergized electric circuit whereby the wire is alternately heated and cooled causing it to expand and contract to oscillate said drum, a pawl cooperating with said ratchet wheel to prevent rotation in one direction and means associatedwith said ratchet wheel for transmitting rotation in the other direction.

7. In a time distributing system of the type where a secondary clock is controlled by a master clock over anelectric circuit, the method of operating the secondary clocks which consists in providing them with thermal responsive escapements and causin the thermal operating said escapements y periodic current impulses sent out by said master clock. 8. An electric clock system comprising an electric circuit, a master clock, a secondary clock, means for imparting motion to said seondary clock, a thermal responsiveelehtric conductor in said circuit for operating said motion im arting means, and means controlled by said master clock for periodically energizing said circuit.

In witness whereof, I- have hereunto set my hand this 20th day of Sept, 1922.

HENRY E. \VARREN. 

